Ability to add emoji / reactions to comments

As a user, I want to respond to comments with an emoji reaction so I can acknowledge someone's comment but not have to write "thanks" and trigger an email to them.

This is similar to how people use Slack. We all want to respond to comments with an emoji instead of saying "thanks" or "got it" or "awesome". I often want to give someone's comment a thumbs up instead of writing a written response, which I know will trigger an email to them.